1. Field of the Invention
The invention relates to furnaces and, more particularly, to a method and apparauts for controlling combustion primarily through regulation of combustion air.
2. Description of the prior art
In the furnace art, it is well known to provide a heat exchanger disposed within a fireplace for receiving heat from the combustion of a solid combustible material such as wood. Unheated air drawn into the heat exchanger is heated and is then discharged into the room to more effectively heat the room. Although this is an obvious improvement over a fireplace having no such heat exchanger, much potentially recoverable energy nevertheless is wasted due to lack of control over the rate of combustion of the combustible material. Prior art attempts to control the rate of combustion have commonly involved the use of doors attached to the front of the fireplace which render the fireplace substantially airtight. In connection therewith, a system of manually actuated dampers is provided adjacent to the doors for regulating the flow of combustion air entering the fireplace. Although such a combustion airflow regulation system in combination with a heat exchanger is superior to a fireplace having only a heat exchanger, obvious difficulties are presented when different combustible materials having varying rates of combustion are employed in the fireplace. Thus, regulation of the rate of combustion is usually troublesome, time consuming and inefficient. It has been discovered that in order to effectively control the burning rate of a solid combustible material, some control must be exercised over the arrangement, or stacking of the combustible material. Prior art grates have failed to do little more than provide a receptacle for the mere deposit of combustible material.
Additional problems exist with conventional heat exchangers. For example, the heat exchanger may be provided with a fan, controlled either manually or thermostatically. Such a fan improves the room heating qualities of the heat exchanger, but with wide variances in heat output. That is, the heat output may be improved with a fan, but temperature variations still will occur because of the varying rate of combustion. Another problem with prior art heat exchangers is the lack of a capability to effectively humidify the heated output air. Attempts at humidification generally have taken the form of a pan of water disposed in the exhaust side of the heat exchanger. This obviously is a crude and inefficient way to humidify the heated air. Yet another problem has been where the combustion process proceeds extremely rapidly. In such a case, such potentially recoverable energy is lost and the combustible material soon is exhausted. It is even possible for furnace temperatures to rise to such a level that components of the heat exchanger are damaged.
Accordingly, it is an object of the invention to efficiently regulate the rate of combustion of combustible material in a furnace.
It is another object of the invention to accomplish such regulation either manually or automatically.
It is a still further object of the invention to provide a new and improved furnace having enhanced combustion and heat transfer efficiency over prior art furnaces.
It is yet another object of the invention to provide a new and improved furnace wherein the heat output of the furnace may be maintained substantially constant.
It is another object of the invention to provide a new and improved furnace wherein heated air exhausted into the room may be efficiently humidified.
It is still another object of the invention to provide a new and improved furnace wherein overtemperature conditions within the furnace may be prevented.